The Solar Ultraviolet Imaging Telescope (SUIT) is an instrument onboard Aditya–L1, the first solar space observatory of the Indian Space Research Organization (ISRO), India, launched on September 2, 2023. SUIT is designed to image the Sun in the 200–400 nm wavelength band in eight narrowband and three broadband filters. SUIT’s science goals start with observing the solar atmosphere and large-scale continuum variations, the physics of solar flares in the NUV region, and many more. The paper elucidates the functioning of the instrument, software packages developed for easier calibration, analysis, and feedback, calibration routines, and the regular maintenance activity of SUIT during the first year of its operation. The paper also describes the various operations performed by SUIT, the program sequences orchestrated to fulfill the mission’s scientific objectives, and highlights some of the notable observations made during its first year of observations.

One of the instruments aboard the Sunrise III mission, the Tunable Magnetograph (TuMag), is a tunable imaging spectropolarimeter in visible wavelengths. It is designed to probe the vector magnetic field and the line-of-sight velocity of the photosphere and the lower chromosphere. The quasi-simultaneous observation of two spectral lines provides excellent diagnostic measurements of the magnetic and dynamic coupling in these layers. The key technologies employed for TuMag are an LCVR-based polarimeter and a solid, LiNbO3 Fabry-Pérot etalon as a spectrometer. However, it also incorporates several innovative features, such as home-made high-sensitivity scientific cameras and a double filter wheel. TuMag can sequentially observe any two out of the three spectral lines of Fe I at 525.02 and 525.06 nm and of Mg I at 517.3 nm. Laboratory measurements have demonstrated outstanding performance, including a wavefront root-mean-square error better than λ/13 for image quality, a full-width-at-half-maximum of 8.7 pm for the filtergraph transmission profile, and polarimetric efficiencies > 0.54. Here we report on the concept, design, calibration, and integration phases of the instrument, as well as on the data reduction pipeline.

We present the multiwavelength study of the ejection of a plasma blob from the limb flare SOL2023-12-31T21:36:00 from NOAA 13536 observed by the Solar Ultraviolet Imaging Telescope (SUIT) on board Aditya-L1. We use SUIT observations along with those from the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory and Spectrometer/Telescope for Imaging X-rays (STIX) on board Solar Orbiter to infer the kinematics and thermal nature of the ejected blob and its connection to the associated flare. The observations show that the flare was comprised of two eruptions. The blob was ejected during the first eruption and later accelerated to velocities over 1500 km s ^−1 measured at a maximum projected height of ∼178 Mm from the Sun’s surface. The acceleration of the ejected plasma blob is cotemporal with the bursty appearance of the hard X-ray light curve recorded by STIX. Radio spectrogram observations from STEREO-A/WAVES and RSTN reveal type III bursts at the same time, indicative of magnetic reconnection. DEM analysis using AIA observations suggests the plasma blob is comprised of cooler and denser plasma in comparison to the ambient corona. To the best of our knowledge, this is the first observation of such a plasma blob in the near-ultraviolet providing crucial measurements for eruption thermodynamics.

The Solar Ultraviolet Imaging Telescope (SUIT) is an instrument on the Aditya-L1 mission of the Indian Space Research Organization (ISRO) launched on 2 September 2023. SUIT continuously provides near-simultaneous full-disk and region-of-interest images of the Sun, slicing through the photosphere and chromosphere and covering a field of view up to 1.5 solar radii. For this purpose, SUIT uses 11 filters tuned at different wavelengths in the 200 – 400 nm range, including the Mg ii h and k and Ca ii H spectral lines. The observations made by SUIT help us understand the magnetic coupling of the lower and middle solar atmosphere. In addition, for the first time, this allows for the measurements of spatially resolved solar broad-band radiation in the near- and mid-ultraviolet, which will help constrain the variability of the solar ultraviolet irradiance in a wavelength range that is central for the chemistry of ozone and oxygen the Earth’s stratosphere. This paper discusses the details of the instrument and data products.

Context. Accurate information on long-term variations in solar irradiance, important for understanding the solar influence on Earth's climate, cannot be derived from direct irradiance measurements due to the comparatively short lifetimes of space-borne experiments. Models using measurements of the solar photospheric magnetic field as input can provide an independent assessment of the changes. Aims. The Spectral And Total Irradiance Reconstruction in the satellite era (SATIRE-S) model does just that. Unfortunately, the magnetogram archives used by SATIRE-S to recover irradiance variations are also relatively short-lived and have short mutual overlapping periods, making it difficult to evaluate their consistency. To overcome this and bridge the various archives more reliably, we include additional input data sets. Methods. We improve SATIRE-S total solar irradiance (TSI) reconstruction by firstly incorporating magnetograms from the Mt Wilson Observatory as well as unsigned magnetograms reconstructed from Meudon, Rome, and San Fernando Ca II K data, and secondly, by re-analysing all periods of overlaps between the various archives. Results. Our combined daily irradiance reconstruction from all eight input archives returns an excellent agreement with direct measurements of irradiance, in particular we find a correlation coefficient of 0.98 when compared to TSIS1/TIM (Total and Spectral Solar Irradiance Sensor Total Irradiance Monitor) data. The minimum-to-minimum TSI difference between 1976 and 2019 is -0.2 +/- 0.17 Wm(-2), while the TSI difference between the 1986 and 2019 minima is statistically insignificant (-0.06 +/- 0.13 Wm(-2)). Our analysis also sheds light on the trend shown by the TSI over the so-called ACRIM gap, disfavouring a hypothesised increasing trend in TSI in that period. Conclusions. By including more direct and indirect magnetogram time series, we have made the TSI reconstructed by SATIRE-S more robust and accurate. The new series shows a reduced trend of decreasing TSI over the last half century, which agrees well with most composites of measured TSI.

The light curves of old G dwarfs obtained in the visible and near-infrared wavelength ranges are highly irregular. This significantly complicates the detectability of the rotation periods of stars similar to the Sun in large photometric surveys, such as Kepler and TESS. In this study, we show that light curves collected in the ultraviolet (UV) wavelength range are much more suitable for measuring rotation periods. Motivated by the observation that the Sun’s rotational period is clearly discernible in the UV part of the spectrum, we study the wavelength dependence of the rotational period detectability. We employ the Spectral and Total Irradiance Reconstructions model to characterize the detectability of the solar rotation period across various wavelengths using the autocorrelation technique. We find that at wavelengths above 400 nm, the probability of detecting the rotation period of the Sun observed at a random phase of its activity cycle is approximately 20%. The probability increases to 80% at wavelengths shorter than 400 nm. These findings underscore the importance of UV stellar photometry.

Solar wind, classified by its bulk speed and the Alfvénic nature of its fluctuations, generates the heliosphere. The elusive physical processes responsible for the generation of the different types of this wind are a topic of active debate. Recent observations reveal intermittent jets, with kinetic energy in the picoflare range, emerging from dark areas of a polar coronal hole threaded by open magnetic field lines. These could substantially contribute to solar wind. However, their ubiquity and direct links to solar wind have not been established. Here, we report a unique set of remote-sensing and in situ observations from the Solar Orbiter spacecraft that establish a unified picture of fast and Alfvénic slow wind, connected to the similar widespread picoflare jet activity in two coronal holes. Radial expansion of coronal holes ultimately regulates the speed of the emerging wind.

Solar flares are regularly observed in extreme-ultraviolet soft X-rays (SXRs) and hard X-rays (HXRs). However, those in near- and mid-ultraviolet are sparse. The Solar Ultraviolet Imaging Telescope (SUIT) on board the Aditya-L1, launched on 2023 September 2, provides regular observations in the 200–400 nm wavelength range through 11 filters. Here, we report the observation of the X6.3 flare on 2024 February 22 using eight narrowband (NB) filters of SUIT. We have also used co-spatiotemporal observations from Solar Dynamics Observatory/Atmospheric Imaging Assembly (SDO/AIA), Solar Orbiter/STIX, GONG H α , Aditya-L1/SoLEXS, and GOES. We obtained light curves over the flaring region from AIA 1600 and 1700 Å and GONG H α and compared them with the disk-integrated light curve obtained from GOES and SoLEXS SXRs and STIX HXRs. We find that the flare peaks in SUIT NB01, NB03, NB04, and NB08 filters simultaneously with HXRs 1600 and 1700 Å, along with the peak temperature obtained from SoLEXS. In contrast, in NB02 and NB05, the flare peaks ∼2 min later than the HXR peak, while in NB06 and NB07, the flare peaks ∼3 min after the GOES SXR peak. To the best of our knowledge, this is the first observation of a flare in these wavelengths (except in NB03, NB04, and NB05). Moreover, for the first time, we show the presence of a bright kernel in NB02. These results demonstrate the capabilities of SUIT observations in flare studies.

In July 2024, Sunrise completed its third successful science flight. The Sunrise iii observatory had been upgraded significantly after the two previous successful flights in 2009 and 2013, to tackle the most recent science challenges concerning the solar atmosphere. Three completely new instruments focus on the small-scale physical processes and their complex interaction from the deepest observable layers in the photosphere up to chromospheric heights. Previously poorly explored spectral regions and lines are exploited to paint a three-dimensional picture of the solar atmosphere with unprecedented completeness and level of detail. The full polarimetric information is captured by all three instruments to reveal the interaction between the magnetic fields and the hydrodynamic processes. Two slit-based spectropolarimeters, the Sunrise UV Spectropolarimeter and Imager (SUSI) and the Sunrise Chromospheric Infrared spectro-Polarimeter (SCIP), focus on the near-ultraviolet (309 – 417 nm) and the near-infrared (765 – 855 nm) regions respectively, and the imaging spectropolarimeter Tunable Magnetograph ( TuMag ) simultaneously obtains maps of the full field-of-view of $46\times 46$ 46 × 46 Mm 2 in the photosphere and the chromosphere in the visible (525 and 517 nm). The instruments are operated in an orchestrated mode, benefiting from a new Image Stabilization and Light Distribution unit ( ISLiD ), with the Correlating Wavefront Sensor (CWS) providing the autofocus control and an image stability with a root-mean-square value smaller than 0.005”. A new gondola was constructed to significantly improve the telescope pointing stability, required to achieve uninterrupted observations over many hours. Sunrise iii was launched successfully on 10 July 2024, from the Esrange Space Center of the Swedish Space Corporation near Kiruna (Sweden). It reached the landing site between the Mackenzie River and the Great Bear Lake in Canada after a flight duration of 6.5 days. In this paper, we give an overview of the Sunrise iii observatory and its instruments.

Identification and understanding of charge conduction mechanisms for functional oxide based devices become necessary to implement any potential applications in spintronics. In this context, present communication deals with the phenomenological percolation model that governs the charge transport properties of chemically grown LaFeO3/La0.7Ca0.3MnO3/SrTiO3 (LFO/LCMO/STO) structure. Various structural aspects have been explored through X-ray diffraction (XRD) measurements. Temperature dependent resistivity behaviors [recorded under current in plane (CIP) mode and current perpendicular to plane (CPP) modes] under different applied magnetic fields have been understood using phenomenological percolation model. In this, phase separation scenario and disordered interface between LFO and LCMO layers have been identified to play effectively their interesting roles. Intrinsic and extrinsic contributions of MR have been identified for both the measurement geometries across LCMO thin film and LFO/LCMO interface. Isothermal magnetoresistance (MR) behaviors have been explained on the basis of universal model for MR isotherms which strongly support the role of electronic phase fluctuations and disordered LFO/LCMO interface. Present research findings demonstrate a practical approach to tune the resistive state of functional oxides by precisely controlling the interface between them. This also serves a better way to control the resistive state of functional oxide thin films by applying external magnetic field and to understand related charge conduction processes.

This Primer provides an overview of a fundamental set of analysis methods for studying waves, vibrations and related oscillatory phenomena — including instabilities, turbulence and shocks — across diverse scientific fields. These phenomena are ubiquitous, from astrophysics to complex systems in terrestrial environments, and understanding them requires careful selection of techniques. Misapplication of analysis tools can introduce misleading results. In this Primer, the fundamental principles of various wave analysis methods are first reviewed, along with adaptations to address complexities such as nonlinear, non-stationary and transient signal behaviour. These techniques are applied to identical synthetic datasets to provide a quantitative comparison of their strengths and limitations. Details are provided to help select the most appropriate analysis tools based on specific data characteristics and scientific goals, promoting reliable interpretations and ensuring reproducibility. Additionally, the Primer highlights best ethical practices for data deposition and the importance of open-code sharing. Finally, the broad applications of these techniques are explored in various research fields, current challenges in wave analysis are discussed, and an outlook on future directions is provided, with an emphasis on potential transformative discoveries that could be made by optimizing and developing cutting-edge analysis methods. Waves are ubiquitous in nature and occur across various scales and settings. In this Primer, Jafarzadeh et al. discuss techniques for preprocessing and analysing waves, including information on choosing the appropriate methods based on wave properties, and present worked examples using synthetic datasets.

TRAPPIST-1 is an M8 dwarf hosting seven known exoplanets and is currently one of the most frequently observed targets of the James Webb Space Telescope (JWST). However, it is notoriously active, and its surface is believed to be covered by magnetic features that contaminate the planetary transmission spectra. The radiative spectra of these magnetic features are needed to clean transmission spectra, but they currently remain unknown. Here, we develop a new approach for measuring these spectra using time-resolved JWST/NIRISS observations. We detect a persistent post-flare enhancement in the spectral flux of TRAPPIST-1. Our analysis rules out lingering flare decay as the cause of the flux enhancement and, thus, points to structural changes on the stellar surface induced by flares. We suggest that the flaring event triggers the disappearance of (part of) a dark magnetic feature, producing a net brightening. This suggestion is motivated by solar data: flare-induced disappearance of magnetic features on the solar surface has been directly detected in high spatial resolution images, and our analysis shows that this process produces changes in solar brightness very similar to those we observe on TRAPPIST-1. The proposed explanation for the flux enhancement enables, to our knowledge, the first measurement of the spectrum of a magnetic feature on an M8 dwarf. Our analysis indicates that the disappearing magnetic feature is cooler than the TRAPPIST-1 photosphere, but by at most a few hundred kelvins.

Sunrise iii is a balloon-borne solar observatory dedicated to investigating the physics governing the magnetism and dynamics in the lower solar atmosphere. The observatory is designed to operate in the stratosphere, at heights around 36 km (above 99

Diluted magnetic semiconductors (DMS) have emerged as promising candidates for spintronic devices, offering a unique combination of semiconducting and magnetic properties. In the present study, ZnO (Z) and Zn0.2Cu0.8O (C) nanostructured materials were synthesized using sol–gel and co–precipitation methods, respectively. Their composite, ZnO: Zn0.2Cu0.8O (ZC), was fabricated to investigate the structural and electrical properties. X–ray diffraction (XRD) analysis confirms the hexagonal wurtzite phase and reveals a reduced crystallite size and suppressed lattice strain across the lattice of ZC composite, as compared to the pure phases (i.e. Z & C). Rietveld refinements and Williamson–Hall (W–H) analysis further established changes in lattice parameters and strain effect. The dielectric constant, measured for a frequency range between 20 Hz and 2 MHz, shows a significant enhancement in its values for composite material which can be attributed to the interfacial polarization and oxygen vacancies. Impedance spectroscopy reveals lower impedance in the ZC composite indicating better conduction pathways due to enhanced defect density and grain boundary interactions. AC conductivity, analyzed using Jonscher's power law, demonstrates that the correlated barrier hopping (CBH) mechanism governs the conduction, with ZC composite sample exhibiting the highest conductivity among all the three samples. These findings suggest that the composite exhibits improved dielectric and electrical performance due to synergistic effects between ZnO and Zn0.2Cu0.8O phases, making it a promising material for electronic and optoelectronic applications.

The Sun's corona is its tenuous outer atmosphere of hot plasma, which is difficult to observe. Most models of the corona extrapolate its magnetic field from that measured on the photosphere (the Sun's optical surface) over a full 27-day solar rotational period, providing a time-stationary approximation. We present a model of the corona that evolves continuously in time, by assimilating photospheric magnetic field observations as they become available. This approach reproduces dynamical features that do not appear in time-stationary models. We used the model to predict coronal structure during the total solar eclipse of 8 April 2024 near the maximum of the solar activity cycle. There is better agreement between the model predictions and eclipse observations in coronal regions located above recently assimilated photospheric data.

Sunrise is a 1-m optical solar observatory carried aloft by a stratospheric balloon. It was developed to study magnetic fields and plasma flows in the solar atmosphere with very high spatial resolution and sensitivity. The Sunrise UV Spectropolarimeter and Imager (SUSI) operates in the 309 - 417 nm range, covering thousands of spectral lines that are poorly accessible from the ground and largely unexplored. The instrument includes a dual-beam polarimeter based on a rotating waveplate, a polarization beam splitter and two custom-made CMOS cameras. SUSI gathers data at high spectral, spatial and temporal resolution. These data are stored onboard during flight. Given that SUSI does not include a polarimetric calibration unit onboard, its polarimetric demodulation matrix is estimated during laboratory calibration measurements prior to its flight. The quality of this calibration is crucial to accurately demodulate the data post-flight and reach the instrument's maximum polarimetric sensitivity goal of 1x10(-3) of the continuum intensity. In this paper, we report the results of eighth polarimetric calibrations of SUSI standalone, acquired at six different wavelengths using artificial LED light sources. The field-dependant demodulation matrices obtained are within the values expected from the design, including their polarimetric efficiencies and temporal stability. The matrices are also confirmed to satisfy the calibration repeatability criterion imposed by the SUSI sensitivity goal.

Accurate calculations of starspot spectra are essential for multiple applications in astronomy. The current standard is to represent starspot spectra by spectra of stars that are cooler than the quiet star regions. This implies approximating a starspot as a nonmagnetic 1D structure in radiative-convective equilibrium, parametrizing convective energy transport by mixing-length theory. It is the inhibition of convection by the starspot magnetic field that is emulated by using a lower spot temperature relative to the quiet stellar regions. Here, we take a different approach, avoiding the approximate treatment of convection and instead self-consistently accounting for the interaction between matter, radiation, and the magnetic field. We simulate spots on G2V, K0V, and M0V stars with the 3D radiative magnetohydrodynamics code MURaM and calculate spectra (R approximate to 500 from 250 to 6000 nm) using ray-by-ray radiative transfer with the MPS-ATLAS code. We find that the 1D models fail to return accurate umbral and penumbral spectra on K0V and M0V stars, where convective and radiative transfer of energy is simultaneously important over a broad range of atmospheric heights, rendering mixing-length theory inaccurate. However, 1D models work well for G2V stars, where both radiation and convection significantly contribute to energy transfer only in a narrow region near the stellar surface. Quantitatively, the 1D approximation leads to errors longward of 500 nm of about 50% for both umbral and penumbral flux contrast relative to quiet star regions on M0V stars and less than 2% (for umbrae) and 10% (for penumbrae) for G2V stars.

The Solar Ultraviolet Imaging Telescope (SUIT) on board the AdityaL1 mission observes the Sun in the 200-400 nm wavelength range. This paper presents the results of various on ground and on board tests and their comparison with the specifications. Moreover, we also present the scheme for data calibration. We demonstrate that the test results are compliant with the specified figures, except the spatial resolution. Such discrepancy will limit the photometric measurements only, at a scale of 2.2" instead of 1.4" as originally envisioned. The results obtained here show that SUIT observations open up a new window for solar observations.

Context. H alpha observations of the solar chromosphere reveal dynamic small-scale structures known as spicules at the limb and rapid blueshifted and redshifted excursions (RBEs and RREs) on-disc. Aims. We want to understand what drives these dynamic features, their magnetohydrodynamic (MHD) properties, and their role in energy and heat transport to the upper solar atmosphere. To do this, we aim to develop a proxy for synthetic H alpha observations in radiative-MHD simulations to help identify these features. Methods. We used the chromospheric extension to the MURaM code (MURaM-ChE) to simulate an enhanced network region. We developed a proxy for H alpha based on a photon escape probability. This is a Doppler-shifted proxy that we used to identify fine structures in the line wings. We studied on-disc features in 3D, obtaining their 3D structure from the absorption coefficient. Results. We validate the H alpha proxy by comparing it against features detected in the wings of H alpha synthesised using MULTI3D. We detect numerous small-scale structures rooted at the network patches, similar to observations in H alpha. The dynamics of an example feature (RBE) at a Doppler shift of 37 km/s show that flux emergence and consequent reconnection drive the formation of this feature. Pressure gradient forces build up to drive a flow along the field line carrying the feature, making it a jet. There is strong viscous and resistive heating on the first appearance of the feature associated with the flux emergence. At the same time and location, a heating front appears and propagates along the field lines at speeds comparable to the Alfv & eacute;n velocity. The feature shows an oscillatory behaviour as it evolves. Conclusions. We show that a synthetic observable based on an escape probability is able to reliably identify features observed with the H alpha spectral line. We demonstrate its applicability by studying the formation, dynamics and properties of an RBE.